John Lott on FBI Active Shooter Records

In all, the FBI claims that concealed handgun permit holders have stopped 3.2 percent of active shooter incidents.

But the bureau misses at least 23 cases where permit holders saved the day. That means they stopped 11.5 percent of active shooter incidents from 2000 to 2017.  We at the Crime Prevention Research Center are more confident that we have all of the cases from 2014 to 2017, when 16.5 percent of attacks were stopped.

Back in 2015, when I pointed out errors in the original report, the FBI simply responded, “We acknowledge in the FBI report that our data are imperfect.”  But no correction was ever made. https://www.realclearpolitics.com/articles/2018/10/23/the_problem_with_the_fbis_active_shooter_data_138425.html